I know this has been posted previously; however, I did not find the posted information helpful and I'm hoping there are people out there who might be able to help me with the issue.

I am trying to find the center of pressure for a vehicle in CFX. I tried both CEL Expressions and the force/torque equations method suggested in previous posts. The first gives me numbers that seem unreasonable. The latter doesn't work either...multiple solutions essentially.

Any other suggestions or any ideas why the CEL Expressions aren't working? I can post up what I used if there are any questions regarding that.

Ok. However, if I try to set up a matrix of the force and torque relations relative to the center of pressure, I get a skew-symmetric matrix which cannot be inverted to solve for the center of pressure.

Is there a way to do this without using the torques and forces method?

Ok. However, if I try to set up a matrix of the force and torque relations relative to the center of pressure, I get a skew-symmetric matrix which cannot be inverted to solve for the center of pressure.

Is there a way to do this without using the torques and forces method?

Thanks, Yakn.

so the only way is to calculate by your self. There is not any feature in CFX in order to obtain the center of pressures. In my case I hace calculated the flow around a rocket and the next step is locating the Cp, but I don't know how to obtain it by CFX... Is very sad use the tipical ms-dos software to obtain the Cp with a basic sketch of my rocket... Can anyone help me?

My original post was incorrect. Yes, you have to calculate it but it is not that hard. From the definition of Torque = r x F, where r is the displacement vector to the point the force acts on and F is the force vector. You can get the torque vector using the torque_x, torque_y and torque_z commands and similarly the forces using force_x, force_y and force_z. It is just then a matter of expanding out the cross product and solving for the displacement vector.

My original post was incorrect. Yes, you have to calculate it but it is not that hard. From the definition of Torque = r x F, where r is the displacement vector to the point the force acts on and F is the force vector. You can get the torque vector using the torque_x, torque_y and torque_z commands and similarly the forces using force_x, force_y and force_z. It is just then a matter of expanding out the cross product and solving for the displacement vector.

Glenn Horrocks

I have calculated the center of pressures obtaining previously the force and the torque pressure net over the surface of my rocket. After that I have made a change of center of reduction of the moment: Mo=Mp+OPxF, where Mp is 0 beacuse P is the center of pressures and I only have had to solve a linear system of equations in order to obtain the coordinates of the center of pressures (OP). In my case "O" is the coordinates origin son P is directly the coordinates of the center of pressures.